There exist known methods for producing three dimensional images in an electronic domain from solid physical objects. Typically, these methods involve some form of data acquisition of information relative to the exterior surfaces of the object, either by contact or non-contact means. The result is a computer generated image of the exterior surface of the object. For example, one such method involves physical contact coordinate measuring methods. This particular method can produce accurate physical part dimensions, but is deficient because it is time consuming to use because of the amount of data generated and because it cannot readily secure interior features of the object. Non-contact methods such as laser scanning are also capable of creating accurate part dimensions, but like the coordinate measuring methods are not readily capable of capturing internal part features. Interior features, such as surface geometries and structural elements cannot readily be captured by these methods and so they are of limited use.
There do exist methods and apparatus for capturing both internal and external features of a physical object. This is a desired and sought after ability both from the stand point of quality control of manufactured parts and because of the desire to be able to reverse engineer objects. Among the methods utilized for these ends are the non-destructive techniques of ultrasound imaging and computed tomography (CT). Ultrasound imaging is generally not accurate for reproducing physical measurements with the desired accuracy. While CT can produce modeling data of the desired accuracy, the equipment used to perform this type of operation or inspection is often quite expensive, with costs for the x-ray producing equipment, the housing for the equipment, the sensors for detecting the x-rays, and the computer resources necessary to operate the CT system often raising the cost to a figure in the one million dollar range. In addition, CT presents a radiation hazard and requires special facilities to use this equipment, which adds to the cost of their acquisition and use. Known methods of quality control and reverse engineering can also require substantial time investments in terms of human time and central processing unit or computer time. A need exists to reduce the time, cost, and repeatability of quality control sampling and to provide manufacturers a way to reliably and accurately reverse engineer an object.
Certain destructive techniques for capturing both internal and external features of a physical object also exist. One of these is disclosed in commonly owned co-pending application Ser. No. 08/284,253, filed Aug. 2, 1994, now U.S. Pat. No. 5,621,648. Another destructive method and apparatus for capturing the internal and external features of a physical object is disclosed in U.S. Pat. No. 5,139,338 which issued to Pomerantz et al. Aug. 18, 1992. Pomerantz discloses apparatus for filling internal cavities in a three-dimensional object and filling the area outside of an object with a support material solidified to a solid block. Following such solidification, a layer of the entire solid block is removed to allow capture of the features of the exposed surface. The support material of Pomerantz is required to have generally the same hardness as that of the object to be analyzed. Further, internal voids in the solidified material are required to be manually filled by first locating the voids and then filling the same in a second step process of encasing the material. This second process requires that the voids first be located before they can be filled. Such a step of location requires further effort such as using non-destructive techniques to locate voids. As has been described, the use of such methods and apparatus for determining internal features is costly and potentially dangerous. Pomerantz contains no accurate method or apparatus for locating and filling voids that may exist within the interior structure of the part to be analyzed.
The existence of voids with the interior features of an object to be analyzed can be extremely detrimental to the accuracy of the representation obtained by the apparatus and process. This is especially true if the voids within the interior features of the object are adjacent to those interior features. In such an instance, a void adjacent a surface internal to the object will create an inaccurate representation of the interior features of the object, and render the representation virtually useless, especially for re-creation of a similar part. A void of filler material adjacent an interior feature of the object to be analyzed will appear to be a part of the object, and therefore render the dimensions obtained from the analysis inaccurate.
It would be desirable to have an apparatus and process for removing voids within the interior filler material of an object to be analyzed, especially voids adjacent an internal surface area of the object, without undo expense or risk.
Presently, various methods exist for the placement of an object to be analyzed so as to allow the introduction of a filler material into the interior and around the exterior of the object. Commonly, a base platform or plate has been used, on which the object is placed. In Pomerantz, for example, the object is aligned on the base and positioned so that it sits upright. Objects may also be suspended above the plate so that the filling material can completely encase the exterior surface of the object. When the encasing material cures, it heats up, also heating the part to be analyzed. When the part heats up, it expands, and has a strong tendency to be forced out of the encasing material. Expansion and contraction of the part creates large forces that the encasing material is incapable of containing.
The advent of the computer and computer aided design (CAD) and computer aided manufacture (CAM) has greatly assisted and expedited the work of the engineer and draftsman in designing, drawing, and manufacturing objects of all kinds. These computer aided engineering tools have made it possible to design a part and manufacture it without ever going through the prototype development stage. The electronic data representing the drawings of these parts are retained in some form of memory, thereby allowing their subsequent access by interested parties. Many parts currently manufactured and sold as well as entire products are made from engineering drawings that were created before the beginning of the CAD/CAM era. Some of these drawings have disappeared or been destroyed and there is a desire to bring these parts and products into the CAD environment.
It would be desirable to have an apparatus and process for taking an existing object and reproducing it in an electronic medium, thereby allowing pre-CAD/CAM era objects to be incorporated into the electronic environment, for providing a less costly alternative quality control inspection method than is presently available, for reducing manufacturing costs and speeding products to market, and for enabling an object to be accurately and quickly reverse engineered.